President Donald Trump on Thursday delayed the full release of JFK assassination records until at the latest 2021, siding with the CIA and FBI over national security concerns that the release of the remaining files could spark.

“I agree with the Archivist’s recommendation that the continued withholdings are necessary to protect against identifiable harm to national security, law enforcement, or foreign affairs that is of such gravity that it outweighs the public interest in immediate disclosure,” Trump wrote in a memorandum released by the White House.

Trump added that need for the continued protection of the documents, “can only grow weaker with the passage of time.”

For now though, the decision to grant additional delays means the president has backtracked from his promise last October. At the time, Trump wrote on Twitter “Subject to the receipt of further information, I will be allowing, as President, the long blocked and classified JFK FILES to be opened.”